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Journal of Ocean University of China 2018年第3期17卷 563-570页

作者： LIANG Dan LIU Chuanlian State Key Laboratory of Marine Geology Tongji University Library Tongji University

Coccolith assemblages in two gravity cores(KX21-2 and KX12-1) from the central Western Pacific Warm Pool(WPWP) have been analyzed with SYRACO. The variations of nutricline and primary productivity(PP) have been reconstructed based on these assemblages. The results show that the coccolith assemblages were dominated by Florisphaera profunda, Gephyrocapsa and Emiliania huxleyi over the last 380 kyr. Variations of nutricline and primary productivity can be divided into three intervals. Interval I(about 380–300 kyr): PP was high and nutricline was shallow; Interval II(about 300–160 kyr): PP decreased dramatically for a short time after the acme of G. caribbeanica in Mid-Brunhes while nutricline became deeper; Interval III(about 160 kyr–present): PP fluctuated at low levels and nutricline was deep. Variations of each coccolith taxon and PP were highly correlated in the two cores, which means that the geological environment is similar in the two cores. Spectrum analysis is performed for all coccolith taxons and PP, and the 19-kyr cycle is the most prominent. It means that the production of coccolithophores in the WPWP is mainly controlled by precession.

关键词： coccolith assemblage Western Pacific Warm Pool primary productivity nutricline precession

Stable isotopic records of the glacial deep-water properties in the South China Sea

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Science China Earth Sciences 1998年第4期41卷 337-344页

作者：翦知湣

Based on the oxygen and carbon stable isotopic records of benthic foraminifera in nine deep-sea cores of the South China Sea (SCS), the bathymetric profiles of δ 18O and δ 13C since the last glacial maximum (LGM) are preliminarily established. The bathymetric gradients of deep-water δ 18O and δ 13C in the SCS are obviously greater during the LGM than during the Holocene, showing the existence of the deep thermocline and nutricline at water depth of about 2 000 m. Particularly, the differences in δ 18O and δ 13C between the LGM and Holocene, from which the ice-volume effect and the global mean shift have been subtracted respectively, are positive values at water depths of 1 000-2 500 m in the SCS. This indicates the existence of deep-water mass with relatively cool temperature or higher salinity, better ventilation and more δ 13C within the water depth range of the SCS during the LGM, which is distinctly different from that at present. These changes further confirm the existence of the glacial "North Pacific Deep Water" which, however, is possibly confined to the water depth range of 1 000-2 500 m.

关键词： stable isotope deep thermocline and nutricline North Pacific Deep Water the South China Sea.

Exploring variations in upper ocean structure for the last 2 Ma of the Nansha area by means of calcareous nannofossils

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Science China Earth Sciences 2001年第10期44卷 905-911页

作者：刘传联成鑫荣 Key Laboratory of Marine Geology Ministry of Education Tongji University Shanghai 200092 China

A great number of calcareous nannofossils have been found in the deep-sea sediments of 2.32 Ma at ODP Site 1143 located in the Nansha area, the southern South China Sea. The number of coccoliths varies from about 0.5×106 up to almost 53×106 coccoliths/g sediment, with an average of 16×106 coccoliths/g sediment. The accumulation rate of total coccoliths varies from 1×106 to 278×106 coccoliths/cm2 ka. The nannofossil assemblages are usually dominated by a lower-photic species-Florisphaera profunda, of which the average percentage is about 70% in all samples. The absolute abundance and the accumulation rate of nannofossils as well as the percentage ofF. profunda display significant oscillations on two different time scales. One is the fluctuation coincident with the glacial-interglacial cycle, and the other is the long-term changes on a time scale longer than 100 ka. Six evolutionary stages of calcareous nannofossils could be divided for the last 2.32 Ma, from which we can reconstruct the changes in the depth of nutricline of the Nansha area. In this paper, the possible mechanism resulting in these variations is also discussed.

关键词： calcareous nannofossil nutricline upper ocean structure Nansha area

Miocene to Pliocene Paleoceanography of the Western Equatorial Pacific Ocean Based on Calcareous Nannofossils, ODP Hole 805B

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Open Journal of Geology 2012年第2期2卷 72-79页

作者： Meutia Farida Ryo Imai Tokiyuki Sato Institute of Applied Earth Sciences Faculty of Engineering and Resource Science Akita University Akita Japan

We describe in detail the Miocene to Quaternary paleoceanography of the western equatorial Pacific Ocean based on calcareous nannofossils of Hole 805B. The relative abundance of Discoaster which lived in the lower photic zone under the stable sea with nutricline and thermocline, decreased step by step at NN5/NN6 and NN10/NN11 boundaries. Al- though the size of Reticulofenestra which is strongly influenced by nutrient, increased five times throughout the section, it drastically decreased in NN4-5 zone, NN10, NN12, and in NN15/NN16 boundary. On the basis of the relationship between Discoaster abundance and Reticulofenestra size change, collapse of the stability of the sea surface in the west- ern equatorial Pacific Ocean progressed step by step throughout the Miocene to Quaternary.

关键词： Paleoceanography Calcareous Nannofossils Discoaster Reticulofenestra nutricline Thermocline

Variations in late Quaternary upper ocean structure of Okinawa Trough:A nannofossil approach

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Science China Earth Sciences 1998年第3期41卷 290-296页

作者：成鑫荣汪品先

The relative abundance ofFlorisphueru profunda, a calcareous nannofossil species in lower euphotic zone, affords an opportunity to study variations in upper ocean structure such as thickness of mixed layer. As revealed by the nannofossil analysis in sediments since 20 ka B. P. from three Okinawa Trough cores, the percentage ofF. profunda increased significantly from glacial to Holocene, with a declining event ca 4 ka B. P. in its southern part. Its downcore trend is similar to that ofPulleniatina obliquiloculuta, a tropical planktonic foraminifera1 species which lives in subsurface water below thermocline in the modern ocean. Their similar variations imply an eastward shift of the Kuroshio Current, a reduction in thickness of the mixed layer, a shallowing of thermocline and a possible increase of turbidity in the upper ocean during the glaciation. The eastward shift of the Kuroshio might be repeated again about 4 ka B.P.

关键词： upper ocean Okinawa Trough calcareous nannofossil nutricline thermocline.